A Generic High-Frequency Model for the Nonlinearities in Buck Converters

To investigate the high-frequency behaviors for the switching converters, the modeling and analysis should include the influences from the sideband components, which are generated by the converter's nonlinearities. With a buck converter, two non- linearities are identified in this paper: the pulse-width modulator and the switches. Based on the harmonic-balance approach, the multifrequency model is proposed to address these nonlinearities and to predict the high-frequency performances. With the derived model, different modulation schemes are compared based on their influence on the sideband effect and the control bandwidth limitations. The possible benefit from the double-edge modulation and its limitations are clarified. In addition, the audio-susceptibility is studied considering the nonlinearity of the switches. With the combination of the two nonlinearities, a generic high-frequency model is achieved. Simulation and experimental results are presented to verify the achievements of the proposed models.

[1]  R. D. Middlebrook,et al.  Low-frequency characterization of switched DC-DC converters , 1972 .

[2]  Peng Xu,et al.  Investigation of candidate VRM topologies for future microprocessors , 2000 .

[3]  F. C. Lee,et al.  Small-signal modeling of series and parallel resonant converters , 1992, [Proceedings] APEC '92 Seventh Annual Applied Power Electronics Conference and Exposition.

[4]  F.C. Lee,et al.  Multifrequency Small-Signal Model for Buck and Multiphase Buck Converters , 2006, IEEE Transactions on Power Electronics.

[5]  Slobodan Cuk,et al.  A general unified approach to modelling switching-converter power stages , 1976, 1970 IEEE Power Electronics Specialists Conference.

[6]  Fred C. Lee,et al.  Design considerations for VRM transient response based on the output impedance , 2003 .

[7]  F.C. Lee,et al.  Analysis of the power delivery path from the 12 V VR to the microprocessor , 2004, Nineteenth Annual IEEE Applied Power Electronics Conference and Exposition, 2004. APEC '04..

[8]  F.C. Lee,et al.  Dynamic current sharing analyses for multiphase buck VRs , 2006, Twenty-First Annual IEEE Applied Power Electronics Conference and Exposition, 2006. APEC '06..

[9]  W. Baumann,et al.  Nonlinear modelling of the PWM switch , 1988, PESC '88 Record., 19th Annual IEEE Power Electronics Specialists Conference.

[10]  Jia Wei,et al.  High Frequency High-Efficiency Voltage Regulators for Future Microprocessors , 2004 .

[11]  R. Tymerski,et al.  Frequency analysis of time-interval-modulated switched networks , 1990, 21st Annual IEEE Conference on Power Electronics Specialists.

[12]  Pradeep Dubey,et al.  Platform 2015: Intel ® Processor and Platform Evolution for the Next Decade , 2005 .

[13]  R.D. Middlebrook,et al.  Sampled-data modeling of switching regulators , 1981, 1981 IEEE Power Electronics Specialists Conference.

[14]  F.C. Lee,et al.  Two-stage approach for 12-V VR , 2004, IEEE Transactions on Power Electronics.

[15]  Peng Xu,et al.  Critical inductance in voltage regulator modules , 2002, APEC. Seventeenth Annual IEEE Applied Power Electronics Conference and Exposition (Cat. No.02CH37335).

[16]  Milan M. Jovanovic,et al.  Design considerations for 12-V/1.5-V, 50-A voltage regulator modules , 2000, APEC 2000. Fifteenth Annual IEEE Applied Power Electronics Conference and Exposition (Cat. No.00CH37058).

[17]  J. Groves.  Small-signal analysis using harmonic balance methods , 1991, PESC '91 Record 22nd Annual IEEE Power Electronics Specialists Conference.

[18]  R. Redl,et al.  Optimizing the load transient response of the buck converter , 1998, APEC '98 Thirteenth Annual Applied Power Electronics Conference and Exposition.